Week 1

Question 1

What are pharmacokinetics?

Answer 1

ADME (Absorption, Distribution, Metabolism, Excretion)
What the animal does to the drug
The movement of drugs within the body

Question 2

What are pharmacodynamics?

Answer 2

What the drug does to the animal

The mechanism of action

Question 3

What is the difference in urine pH between herbivores and carnivores?

Answer 3

Carnivores have more acidic urine pH, herbivores more alkaline

Question 4

What metabolic enzyme are cats deficient in?

Answer 4

glucuronyl transferase (glucuronidation)

Question 5

What drug class do Boxers have a sensitivity to and how does it manifest?

Answer 5

Phenothiazines –> cardiovascular effects

Question 6

What drug do Collies have a sensitivity to and how does it manifest?

Answer 6

Ivermectin –> CNS effects (ataxia, tremors, salivation, coma)

Genetic factors cause this

Question 7

What drug do Australian Terriers have a sensitivity to and how does it manifest?

Answer 7

Droperidol/fentanyl –> no sedation/analgesia but salivation, tachycardia, muscle tremors and convulsions may be seen

Question 8

What are the factors related to young animal drug metabolism?

Answer 8

Decreased metabolism and excretion
Increased BBB permeability
Decreased plasma protein binding
Increased total body water
Susceptible to some adverse effects (tetracyclines yellow teeth, fluoroquinolones damage cartilage, steroids prematurely close epiphysis)

Question 9

What are the factors related to old animal drug metabolism?

Answer 9

Decreased metabolism and excretion
Reduced cardiac output and hepatic blood flow
Chronic diseases
Changes in body composition (reduced lean body mass, total body water and plasma proteins; increased body fat)

Question 10

Examples of how disease can affect drug metabolism

Answer 10

Liver disease decreases drug metabolism
Renal disease decreases drug excretion
Congestive heart failure decreases drug distribution and excretion

Question 11

Describe and give examples of idiosyncratic drug reactions.

Answer 11

Unpredictable abnormal reaction- may have genetic component, NOT dependent on dose, requires drug withdrawal and is caused by reactive drug metabolites.
Examples: Liver damage by griseofulvin in some cats, facial excoriation with methimazole in some cats.

Question 12

Describe hypersensitivity.

Answer 12

Some drugs act as antigens (e.g. blood, plasma, protein hormones) or haptens (e.g. penicillins, sulfonamides, aspirin).
Prior exposure to the drug is necessary!
Cross sensitivity
Type I hypersensitivity (allergy and/or anaphylaxis)

Question 13

Define tolerance.

Answer 13

Gradual decrease in responsiveness to chronic drug administration (e.g. opioids)

Question 14

Define tachyphylaxis.

Answer 14

An acute form of tolerance (e.g. ephedrine)

Question 15

Name some pharmacokinetic mechanisms of tolerance.

Answer 15

Altered absorption of the drug
Enzyme induction (increased metabolism of the drug)
Increased active excretion of the drug

Question 16

Name some pharmacodynamic mechanisms of tolerance.

Answer 16

Desensitization (receptor down-regulation)
Loss of receptor
Exhaustion of mediator

Question 17

Define cumulation and give examples.

Answer 17

The rate of elimination is slower than the rate of absorption.
Examples: digitalis, phenylbutazone, thiopental

Question 18

What are some examples of beneficial drug-drug interactions?

Answer 18

Trimethoprim and sulfonamide

ACE inhibitor and thiazide diuretic

Question 19

What are some examples of detrimental drug-drug interactions?

Answer 19

Aminoglycoside and muscle relaxant

Chloramphenicol and phenoparbitol

Question 20

Define chemical antagonism.

Answer 20

Drugs react chemically to inactivate each other.

In vitro or in vivo (e.g. tetracyclines and calcium)

Question 21

Define physiological antagonism.

Answer 21

Drugs work in different ways and have opposing effects that cancel each other out

Question 22

Define pharmacokinetic antagonism

Answer 22

One drug reduces the concentration of the other at its site of action by interfering with its ADME process

Question 23

Define receptor antagonism

Answer 23

One drug bind to a receptor and prevents the other drug from having its normal activity at that receptor

Question 24

Describe how pharmacokinetic antagonism can affect drug absorption.

Answer 24

One drug can inhibit the absorption of another such as SQ epinephrine and lidocaine. In this case it’s good bc epinephrine vasoconstricts, keeping lidocaine in one place.
One drug can enhance the absorption of another (e.g. topical DMSO and griseofulvin)

Question 25

Describe how pharmacokinetic antagonism can affect drug distribution.

Answer 25

Competition for binding sites on plasma proteins (e.g. warfarin and phenylbutazone)

Question 26

Describe how pharmacokinetic antagonism can affect drug metabolism.

Answer 26

Enzyme inducers (e.g. phenobarbital, rifampin, griseofulvin, kale)
Enzyme inhibitors (e.g. chloramphenicol, cimetidine, ketoconazole, grapefruit)

Question 27

Describe how pharmacokinetic antagonism can affect drug excretion.

Answer 27

Competition for carrier molecules (e.g. probenecid and penicillin)
Changes in urinary pH- acidifying the urine increases excretion of weak bases and alkalinizing the urine increases excretion of weak acids.

Question 28

Define drug disposition

Answer 28

Study of movement of drugs across biological membranes in the body from the time of absorption until elimination (ADME process)

Question 29

Name the types of passive diffusion.

Answer 29

Paracellular movement (intercellular aqueous channels)
Transmembrane movement (through lipid membranes and aqueous protein channels, bulk flow --> small water-soluble molecules move with water)
Movement across a concentration gradient

Question 30

What are the coefficients that control passive diffusion?

Answer 30

Lipid/water partition coefficient (lipid solubility, when higher crosses membrane faster)
Diffusion coefficient (diffusional mobility measure, molecular size, conformation, ionization degree)